360 research outputs found
Mean Field Method Applied To The New World Sheet Field Theory: String Formation
The present article is based on a previous one, where a second quantized
field theory on the world sheet for summing the planar graphs of phi^3 theory
was developed. In this earlier work, the ground state of the model was
determined using a variational approximation. Here, starting with the same
world sheet theory, we instead use the mean field method to compute the ground
state, and find results in agreement with the variational calculation. Apart
from serving as a check on the variational calculation, the mean field method
enables us to go beyond the ground state to compute the excited states of the
model. The spectrum of these states is that of a string with linear
trajectories, plus a continuum that starts at higher energy. We show that, by
appropriately tuning the parameters of the model, the string spectrum can be
cleanly seperated from the continuum.Comment: 27 pages, 5 figures, typos correcte
Covariant And Local Field Theory On The World Sheet
In earlier work, using the light cone picture, a world sheet field theory
that sums planar phi^3 graphs was constructed and developed. Since this theory
is both non-local and not explicitly Lorentz invariant, it is desirable to have
a covariant and local alternative. In this paper, we construct such a covariant
and local world sheet theory, and show that it is equivalent to the original
non-covariant version.Comment: 22 pages,3 figures, typos and eqs.(11) and (63) are correcte
Electrospray painted article containing thermally exfoliated graphite oxide and method for their manufacture
A painted polymer part containing a conductive polymer composition containing at least one polymer and a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, wherein the painted polymer part has been electrospray painted
Field Theory On The World Sheet: Improvements And Generalizations
This article is the continuation of a project of investigating planar phi^3
model in various dimensions. The idea is to reformulate them on the world
sheet, and then to apply the classical (meanfield) approximation, with two
goals: To show that the ground state of the model is a solitonic configuration
on the world sheet, and the quantum fluctuations around the soliton lead to the
formation of a transverse string. After a review of some of the earlier work,
we introduce and discuss several generalizations and new results. In 1+2
dimensions, a rigorous upper bound on the solitonic energy is established. A
phi^4 interaction is added to stabilize the original phi^3 model. In 1+3 and
1+5 dimensions, an improved treatment of the ultraviolet divergences is given.
And significantly, we show that our approximation scheme can be imbedded into a
systematic strong coupling expansion. Finally, the spectrum of quantum
fluctuations around the soliton confirms earlier results: In 1+2 and 1+3
dimensions, a transverse string is formed on the world sheet.Comment: 29 pages, 5 figures, several typos and eqs.(74) and (75) are
corrected, a comment added to section
More On The Connection Between Planar Field Theory And String Theory
We continue work on the connection between world sheet representation of the
planar phi^3 theory and string formation. The present article, like the earlier
work, is based on the existence of a solitonic solution on the world sheet, and
on the zero mode fluctuations around this solution. The main advance made in
this paper is the removal of the cutoff and the transition to the continuum
limit on the world sheet. The result is an action for the modes whose energies
remain finite in this limit (light modes). The expansion of this action about a
dense background of graphs on the world sheet leads to the formation of a
string.Comment: 27 pages, 3 figure
Functionalized Graphene Sheets Having High Carbon to Oxygen Ratios
Functionalized graphene sheets having a carbon to oxygen molar ratio of at least about 23:1 and method of preparing the same
Kinematic modelling of a 3-axis NC machine tool in linear and circular interpolation
Machining time is a major performance criterion when it comes to high-speed
machining. CAM software can help in estimating that time for a given strategy.
But in practice, CAM-programmed feed rates are rarely achieved, especially
where complex surface finishing is concerned. This means that machining time
forecasts are often more than one step removed from reality. The reason behind
this is that CAM routines do not take either the dynamic performances of the
machines or their specific machining tolerances into account. The present
article seeks to improve simulation of high-speed NC machine dynamic behaviour
and machining time prediction, offering two models. The first contributes
through enhanced simulation of three-axis paths in linear and circular
interpolation, taking high-speed machine accelerations and jerks into account.
The second model allows transition passages between blocks to be integrated in
the simulation by adding in a polynomial transition path that caters for the
true machining environment tolerances. Models are based on respect for path
monitoring. Experimental validation shows the contribution of polynomial
modelling of the transition passage due to the absence of a leap in
acceleration. Simulation error on the machining time prediction remains below
1%
Coatings Containing Functionalized Graphene Sheets and Articles Coated Therewith
Coatings are provided containing functionalized graphene sheets and at least one binder. In one embodiment, the coatings are electrically conductive
Printed electronics
Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed
Printed Electronics
Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed
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