16,365 research outputs found
Segregation in a fluidized binary granular mixture: Competition between buoyancy and geometric forces
Starting from the hydrodynamic equations of binary granular mixtures, we
derive an evolution equation for the relative velocity of the intruders, which
is shown to be coupled to the inertia of the smaller particles. The onset of
Brazil-nut segregation is explained as a competition between the buoyancy and
geometric forces: the Archimedean buoyancy force, a buoyancy force due to the
difference between the energies of two granular species, and two geometric
forces, one compressive and the other-one tensile in nature, due to the
size-difference. We show that inelastic dissipation strongly affects the phase
diagram of the Brazil nut phenomenon and our model is able to explain the
experimental results of Breu et al. (PRL, 2003, vol. 90, p. 01402).Comment: 5 pages, 2 figure
Information Acquisition and Investment Decisions on the Internet: An Empirical Investigation
With intensifying competition, the significance of understanding customer characteristics related to information acquisition and decision making on the Internet has increased. An understanding of customer characteristics can become a crucial element in the development and implementation of marketing strategy. This paper examines the influence of some key demographic and psychological variables on information acquisition and investment decisions on the Internet, related to mutual funds. Findings indicate that product familiarity, age, and information breadth significantly influenced information acquisition. For investment decisions on the Internet, in addition to the above-mentioned variables, sex and overconfidence was also significant
Parameters for Systems Exhibiting Local Lattice Distortions, Charge and Spin Ordering
Keeping in mind the experimental results that indicate local lattice
distortions, charge and spin orderings, we have developed a phenomenological
approach which allows us to describe the electronic phase diagram of cuprates
and related systems in terms of few parameters.In the present work we consider
a third-order parameter theory which characterize charge, spin and
superconductivity orderings. We are thus led to a theory of three scalar
fields. By coupling these scalars to gauge fields we are naturally led to
string-like solutions, which we interpret as stripes. This ties nicely with our
quantum group conjecture that 1d systems play an important role in the physics
of cuprates and related materials. We show that this simple approach can give
rough values for two-order parameters which can be naively be interpreted as
charge and spin orderings. We also report our attempt to understand how local
lattice distortions are involved and what role they play in terms of these two
order parameters.Comment: 8 pages revtex, Published in AIP Conference Proceedings 554: Int.
Sym. on Physics in Local Lattice Distortions, July 23-26, 200
Selection from Multivariate Normal Populations
Selection from multivariate normal population
Seismic vulnerability assessment and evaluation of high rise buildings in Islamabad
Primarily the aim of this research is to carry out seismic evaluation study of buildings structures in Islamabad in order to propose basic guidelines and suggestions for Pakistan Code. Knowing the important nature of the subject, the earthquake based organizations are serious to compile a document for seismic threatened countries and areas. It is aimed that the document will work as a guideline source for the seismic evaluation, calculation and assessment of strength, behavior and expected performance and also the safety of already existing buildings. This study is based on review of already available documents on seismic vulnerability and evaluation of present buildings at different sites is carried out in order to know the key components of this very procedure so that it can be used in Pakistan and also in other developing countries as well. This would not only be robust, safe and reliable, but also can be convenient to use within the domain of available resources. ASCE 31-03 guidelines among the available documents are considered to be a suitable and the most reliable for to be in Pakistan
Phase-coexisting patterns, horizontal segregation and controlled convection in vertically vibrated binary granular mixtures
We report new patterns, consisting of coexistence of sub-harmonic/harmonic
and asynchronous states [for example, a granular gas co-existing with (i)
bouncing bed, (ii) undulatory subharmonic waves and (iii) Leidenfrost-like
state], in experiments on vertically vibrated binary granular mixtures in a
Heleshaw-type cell. Most experiments have been carried out with equimolar
binary mixtures of glass and steel balls of same diameter by varying the total
layer-height () for a range of shaking acceleration (). All patterns
as well as the related phase-diagram in the ()-plane have been
reproduced via molecular dynamics simulations of the same system. The
segregation of heavier and lighter particles along the horizontal direction is
shown to be the progenitor of such phase-coexisting patterns as confirmed in
both experiment and simulation. At strong shaking we uncover a {\it partial}
convection state in which a pair of convection rolls is found to coexist with a
Leidenfrost-like state. The crucial role of the relative number density of two
species on controlling the buoyancy-driven granular convection is demonstrated.
A possible model for spontaneous horizontal segregation is suggested based on
anisotropic diffusion
Estimation of losses for adobe buildings in Pakistan
Adobe buildings are vulnerable to seismic forces. Large scale destructions and casualties have been caused due
to the collapse of adobe buildings during the past earthquakes. A significant number of adobe structures exist in
different parts of Pakistan, similar to other parts of the world. Since Pakistan lies in a seismic active region, it is
necessary to assess the level of vulnerability of these buildings in order to estimate associated losses during a
seismic event. This paper presents the results of a study which was conducted to quantify damages to adobe
buildings based on their fragility curves. The adobe buildings were found to be highly vulnerable to low intensity
earthquakes. The vulnerability of these buildings has been compared with the European adobe buildings. It was
noted that Pakistani adobe buildings were slightly less resistant to earthquakes as compared to similar buildings
in Europe. Retrofitting solutions were suggested in order to increase the seismic capacity of adobe buildings in
Pakistan
SET based experiments for HTSC materials: II
The cuprates seem to exhibit statistics, dimensionality and phase transitions
in novel ways. The nature of excitations
[i.e. quasiparticle or collective], spin-charge separation, stripes [static
and dynamics], inhomogeneities, psuedogap, effect of impurity dopings [e.g. Zn,
Ni] and any other phenomenon in these materials must be consistently
understood. In this note we further discuss our original suggestion of using
Single Electron Tunneling Transistor
[SET] based experiments to understand the role of charge dynamics in these
systems. Assuming that SET operates as an efficient charge detection system we
can expect to understand the underlying physics of charge transport and charge
fluctuations in these materials for a range of doping. Experiments such as
these can be classed in a general sense as mesoscopic and nano characterization
of cuprates and related materials. In principle such experiments can show if
electron is fractionalized in cuprates as indicated by ARPES data. In contrast
to flux trapping experiments SET based experiments are more direct in providing
evidence about spin-charge separation. In addition a detailed picture of nano
charge dynamics in cuprates may be obtained.Comment: 10 pages revtex plus four figures; ICMAT 2001 Conference Symposium P:
P10-0
Mapping Mutual Fund Investor Characteristics and Modeling Switching Behavior
Securing a mutual fund that meets investment goals is an important reason why some investors exclusively stay with a particular mutual fund and others switch funds within their fund family. This paper empirically investigates investor attitudes toward mutual funds. Our model, based on investor responses, develops an investor\u27s risk profile variable. Results indicate that regardless of whether the investors invest in nonemployer plans or in both employer and nonemployer plans, they consider their investment risk, fund performance, investment mix, and the capital base of the fund before switching funds. The model developed in this study can also assist in predicting investors\u27 switching behavior
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