154,229 research outputs found
A Study of Anyon Statistics by Breit Hamiltonian Formalism
We study the anyon statistics of a dimensional Maxwell-Chern-Simons
(MCS) gauge theory by using a systemmetic metheod, the Breit Hamiltonian
formalism.Comment: 25 pages, LATE
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A New Layer Casting System for Ceramic Laser Rapid Prototyping Apparatus
In the existing Ceramic Laser Fusion system, slurry is fed on the high
temperature surface of the green part; therefore, a part of water infiltrates into the
green block and vaporizes before the process of layer casting. As a result, the slurry
viscosity rises gradually; the quality of the layer surface is not uniform, and the green
part density is uneven. The aim of present study is to develop a new layer casting
system which can solve the problems mentioned above to obtain a green part with
uniform surface quality and density, and to shorten the time-taken of part fabrication.
The first part of the paper illustrates the major requirements and parameters of a slurry
distributor; the second part describes the integration of the slurry feeding device and
layer casting system. The integrated system can feed slurry and cast thin layer
simultaneously; consequently, the drawbacks of the existing system can be eliminated
and the time-taken of the layer casting can be shortened. A variable-frequency drive
(inverter) is used to control the motor speed. The relation between the frequency and
the slurry delivery can be included in the process control program to adjust the
quantity in accordance with the layer thickness; hence, the waste of the slurry can be
reduced.Mechanical Engineerin
A magnetically driven origin for the low luminosity GRB 170817A associated with GW170817
The gamma-ray burst GRB 170817A associated with GW170817 is subluminous and
subenergetic compared with other typical short GRBs. It may be due to a
relativistic jet viewed off-axis, or a structured jet, or cocoon emission.
Giant flares from magnetars may possibly be ruled out. However, the luminosity
and energetics of GRB 170817A is coincident with that of magnetar giant flares.
After the coalescence of the binary neutron star, a hypermassive neutron star
may be formed. The hypermassive neutron star may have magnetar-strength
magnetic field. During the collapse of the hypermassive neutron star, the
magnetic field energy will also be released. This giant-flare-like event may
explain the the luminosity and energetics of GRB 170817A. Bursts with similar
luminosity and energetics are expected in future neutron star-neutron star or
neutron star-black hole mergers.Comment: 6 pages, 1 figure, accepted in Research in Astronomy and Astrophysic
Ku-band field-effect power transistors
A single stage amplifier was developed using an 8 gate, 1200 micrometer width device to give a gain of 3.3 + or - 0.1 dB over the 14.4 to 15.4 GHz band with an output power of 0.48 W and 15% minimum efficiency with 0.255 W of input power. With two 8 gate devices combined and matched on the device carrier, using a lumped element format, a gain of 3 dB was attained over the 14.5 to 15.5 GHz band with a maximum efficiency of 9.9% for an output power of 0.8 W
Classical Extended Conformal Algebras Associated with Constrained KP Hierarchy
We examine the conformal property of the second Hamiltonian structure of
constrained KP hierarchy derived by Oevel and Strampp. We find that it
naturallygives a family of nonlocal extended conformal algebras. We give two
examples of such algebras and find that they are similar to Bilal's V algebra.
By taking a gauge transformation one can map the constrained KP hierarchy to
Kuperschmidt's nonstandard Lax hierarchy. We consider the second Hamiltonian
structure in this representation. We show that after mapping the Lax operator
to a pure differential operator the second structure becomes the sum of the
second and the third Gelfand-Dickey brackets defined by this differential
operator. We show that this Hamiltonian structure defines the W-U(1)-Kac-Moody
algebra by working out its conformally covariant form.Comment: NHCU-HEP-94-28, 19 pages (Plain TeX
Energy Efficient User Association and Power Allocation in Millimeter Wave Based Ultra Dense Networks with Energy Harvesting Base Stations
Millimeter wave (mmWave) communication technologies have recently emerged as
an attractive solution to meet the exponentially increasing demand on mobile
data traffic. Moreover, ultra dense networks (UDNs) combined with mmWave
technology are expected to increase both energy efficiency and spectral
efficiency. In this paper, user association and power allocation in mmWave
based UDNs is considered with attention to load balance constraints, energy
harvesting by base stations, user quality of service requirements, energy
efficiency, and cross-tier interference limits. The joint user association and
power optimization problem is modeled as a mixed-integer programming problem,
which is then transformed into a convex optimization problem by relaxing the
user association indicator and solved by Lagrangian dual decomposition. An
iterative gradient user association and power allocation algorithm is proposed
and shown to converge rapidly to an optimal point. The complexity of the
proposed algorithm is analyzed and the effectiveness of the proposed scheme
compared with existing methods is verified by simulations.Comment: to appear, IEEE Journal on Selected Areas in Communications, 201
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