3,128 research outputs found
A Simple Statistical Model for Analysis of QGP-droplet (Fireball) Formation
We construct the density of states for quarks and gluons using the `Thomas -
Fermi model' for atoms and the `Bethe model' for nucleons as templates. With
parameters to take care of the plasma (hydrodynamical) features of the QGP with
a thermal potential for the interaction, we find a window in the parametric
space of the model where observable QGP droplets of 5 fm radius can
occur with transition temperature in the range 140 MeV to 250 MeV. By matching
with the expectations of Lattice Gauge estimates of the QGP-hadron transitions,
we can further narrow the window, thereby restricting the allowed values of the
flow-parameters of the model.Comment: LaTex 11 pages, 8 figure
Influence of analysis and design models on minimum weight design
The results of numerical experiments designed to illustrate how the minimum weight design, accuracy, and cost can be influenced by: (1) refinement of the finite element analysis model and associated load path problems, and (2) refinement of the design variable linking model are examined. The numerical experiments range from simple structures where the modelling decisions are relatively obvious and less costly to the more complex structures where such decisions are less obvious and more costly. All numerical experiments used employ the dual formulation in ACCESS-3 computer program. Guidelines are suggested for creating analysis and design models that predict a minimum weight structure with greater accuracy and less cost. These guidelines can be useful in an interactive optimization environment and in the design of heuristic rules for the development of knowledge-based expert optimization systems
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The effect of soil moisture perturbations on Indian Monsoon Depressions in a numerical weather prediction model
Indian monsoon depressions (MDs) are synoptic-scale cyclonic systems that propagate across peninsular India three or four times per monsoon season. They are responsible for the majority of rainfall in agrarian north India, thus constraining precipitation estimates is of high importance. Here, we use a case study from August 2014 to explore the relationship between varying soil moisture and the resulting track and structure of an incident MD using the Met Office Unified Model. We use this case study with the view to increasing understanding of the general impact of soil moisture perturbations on monsoon depressions. It is found that increasing soil moisture in the monsoon trough region results in deeper inland penetration and a more developed structure - e.g. a warmer core in the mid-troposphere and a stronger bimodal potential vorticity core in the middle/lower troposphere - with more precipitation, and a
structure that in general more closely resembles that found in depressions over the ocean, indicating that soil moisture may enhance the convective mechanism that drives depressions over land. This experiment also shows that these changes are most significant when the depression is deep, and negligible when it is weakening. Increasing soil moisture in the sub-Himalayan arable zone, a region with large irrigation coverage, also caused deeper inland penetration and some feature enhancement in the upper troposphere but no significant changes were found in the track heading or lower-tropospheric structure
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