22,557 research outputs found
Remark about Non-BPS D-Brane in Type IIA Theory
In this paper we would like to show simple mechanisms how from the action for
non-BPS D-brane we can obtain action describing BPS D(p-1)-brane in Type IIA
theory.Comment: 13 pages, completely rewritten pape
Characterization and comparative evaluation of novel planar electromagnetic sensors
The characterization of three types of novel planar electromagnetic sensors: 1) meander; 2) mesh; and 3) interdigital configuration, has been studied and their comparative performance has been evaluated based on their areas of applications. All of them are suitable for inspection and evaluation of system properties without destroying them. The experiments on fabricated sensors have been conducted and the results are presented here. The target application is to use a mixture of different types of sensors to detect plasti
A wave driver theory for vortical waves propagating across junctions with application to those between rigid and compliant walls
A theory is described for propagation of vortical waves across alternate rigid and compliant panels. The structure in the fluid side at the junction of panels is a highly vortical narrow viscous structure which is idealized as a wave driver. The wave driver is modelled as a ‘half source cum half sink’. The incoming wave terminates into this structure and the outgoing wave emanates from it. The model is described by half Fourier–Laplace transforms respectively for the upstream and downstream sides of the junction. The cases below cutoff and above cutoff frequencies are studied. The theory completely reproduces the direct numerical simulation results of Davies & Carpenter (J. Fluid Mech., vol. 335, 1997, p. 361). Particularly, the jumps across the junction in the kinetic energy integral, the vorticity integral and other related quantities as obtained in the work of Davies & Carpenter are completely reproduced. Also, some important new concepts emerge, notable amongst which is the concept of the pseudo group velocity
A low-cost sensing system for quality monitoring of dairy products
The dairy industry is in need of a cost-effective, highly reliable, very accurate, and fast measurement system to monitor the quality of dairy products. This paper describes the design and fabrication works undertaken to develop such a system. The techniques used center around planar electromagnetic sensors operating with radio frequency excitation. Computer-aided computation, being fast, facilitates on-line monitoring of the quality. The sensor technology proposed has the ability to perform volumetric penetrative measurements to measure properties throughout the bulk of the product
Cosmological Rescaling through Warped Space
We discuss a scenario where at least part of the homogeneity on a brane world
can be directly related to the hierarchy problem through warped space. We study
the dynamics of an anti-D3-brane moving toward the infrared cut-off of a warped
background. After a region described by the DBI action, the self-energy of the
anti-D3-brane will dominate over the background. Then the world-volume scale of
the anti-D3-brane is no longer comoving with the background geometry. After it
settles down in the infrared end, the world-volume inhomogeneity will appear,
to a Poincare observer, to be stretched by an exponentially large ratio. This
ratio is close to that of the hierarchy problem between the gravitational and
electroweak scales.Comment: 12 pages, 2 figures; v2, PRD version, comments and references adde
Multi-Throat Brane Inflation
We present a scenario where brane inflation arises more generically. We start
with D3 and anti-D3-branes at the infrared ends of two different throats. This
setup is a natural consequence of the assumption that in the beginning we have
a multi-throat string compactification with many wandering anti-D3-branes. A
long period of inflation is triggered when D3-branes slowly exit the highly
warped infrared region, under a potential generically arising from the moduli
stabilization. In this scenario, the usual slow-roll conditions are not
required, and a large warping is allowed to incorporate the Randall-Sundrum
model.Comment: 11 pages; v3: minor revision, PRD versio
Cosmological Solution from D-brane motion in NS5-Branes background
We study dynamics of a D3-brane propagating in the vicinity of k coincident
NS5 branes. We show that when is small, there exists a regime in which
dynamics of the D-brane is governed by Dirac-Born-Infeld action while higher
order derivative in the expansion can not be neglected. This leads to a
restriction on how fast scalar field may roll. We analyze the motion of a
rolling scalar field in this regime, and extend the analysis to cosmological
systems obtained by coupling this type of field theory to four dimensinal
gravity. It also leads to some FRW cosmologies, some of which are related to
those obtained with tachyon matter.Comment: 15 pages, To appear in International Journal of Modern Physics
A note on the decay of noncommutative solitons
We propose an ansatz for the equations of motion of the noncommutative model
of a tachyonic scalar field interacting with a gauge field, which allows one to
find time-dependent solutions describing decaying solitons. These correspond to
the collapse of lower dimensional branes obtained through tachyon condensation
of unstable brane systems in string theory.Comment: 8 pages, no figures. Extended version, references adde
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