26,611 research outputs found
Pion and Kaon Condensation at Finite Temperature and Density
In this paper, we study O(2N)-symmetric -theory at finite temperature
and density using the 2PI-1/N expansion. As specific examples, we consider pion
condensation at finite isospin chemical potential and kaon condensation at
finite chemical potential for hyper charge and isospin charge. We calculate the
phase diagrams and the quasiparticle masses for pions and kaons in the large-N
limit. It is shown that the effective potential and the gap equation can be
renormalized by using local counterterms for the coupling constant and mass
parameter, which are independent of temperature and chemical potentials.Comment: 10 pages. 7 Figures. v2: Better plots and figs. Added significant
number of refs v3: Accepted for publication in PRD. Added a figure and
improved part on renormalization as well as presentatio
Hybrid HVDC for supply of power to offshore oil platforms
A HVDC hybrid system, comprising a line commutated thyristor HVDC converter and a STATCOM, is proposed in this paper for supplying power to offshore oil platforms that do not have their own generation. The proposed system combines the robust performance, low capital cost and low power loss of a line commutated HVDC converter, with the fast dynamic performance of an equivalent VSC Transmission system. The paper describes the principles and control strategies of the proposed system. PSCAD/EMTDC simulations are presented to demonstrate the robust performance of the system using case studies of various operating conditions such as black-start, load perturbations, AC fault conditions and disturbance caused by the starting of large local induction machines
Anisotropy study of multiferroicity in the pyroxene NaFeGeO
We present a study of the anisotropy of the dielectric, magnetic and
magnetoelastic properties of the multiferroic clinopyroxene NaFeGeO.
Pyroelectric currents, dielectric constants and magnetic susceptibilities as
well as the thermal expansion and the magnetostriction were examined on large
synthetic single crystals of NaFeGeO. The spontaneous electric
polarization detected below K in an
antiferromagnetically ordered state ( K) is mainly lying
within the plane with a small component along , indicating a triclinic
symmetry of the multiferroic phase of NaFeGeO. The electric
polarization can be strongly modified by applying magnetic fields along
different directions. We derive detailed magnetic-field versus temperature
phase diagrams and identify three multiferroic low-temperature phases, which
are separated by a non-ferroelectric, antiferromagnetically ordered state from
the paramagnetic high-temperature phase.Comment: 14 pages, 8 figures. (minor modifications and corrections of the
text
Observation of twin beam correlations and quadrature entanglement by frequency doubling in a two-port resonator
We demonstrate production of quantum correlated and entangled beams by second
harmonic generation in a nonlinear resonator with two output ports. The output
beams at wavelength 428.5 nm exhibit 0.9 dB of nonclassical intensity
correlations and 0.3 dB of entanglement.Comment: 5 pages, 7 figure
Feedback Enhanced Sensitivity in Optomechanics: Surpassing the Parametric Instability Barrier
The intracavity power, and hence sensitivity, of optomechanical sensors is
commonly limited by parametric instability. Here we characterize the parametric
instability induced sensitivity degradation in a micron scale cavity
optomechanical system. Feedback via optomechanical transduction and electrical
gradient force actuation is applied to suppress the parametric instability. As
a result a 5.4 fold increase in mechanical motion transduction sensitivity is
achieved to a final value of .Comment: 4 pages, 4 figure
Use of ERTS data for a multidisciplinary analysis of Michigan resources
The author has identified the following significant results. The results of this investigation of ratioing simulated ERTS spectral bands and several non-ERTS bands (all collected by an airborne multispectral scanner) indicate that significant terrain information is available from band-ratio images. Ratio images, which are based on the relative spectral changes which occur from one band to another, are useful for enhancing differences and aiding the image interpreter in identifying and mapping the distribution of such terrain elements as seedling crops, all bare soil, organic soil, mineral soil, forest and woodlots, and marsh areas. In addition, the ratio technique may be useful for computer processing to obtain recognition images of large areas at lower costs than with statistical decision rules. The results of this study of ratio processing of aircraft MSS data will be useful for future processing and evaluation of ERTS-1 data for soil and landform studies. Additionally, the results of ratioing spectral bands other than those currently collected by ERTS-1 suggests that some other bands (particularly a thermal band) would be useful in future satellites
The Stability Balloon for Two-dimensional Vortex Ripple Patterns
Patterns of vortex ripples form when a sand bed is subjected to an
oscillatory fluid flow. Here we describe experiments on the response of regular
vortex ripple patterns to sudden changes of the driving amplitude a or
frequency f. A sufficient decrease of f leads to a "freezing" of the pattern,
while a sufficient increase of f leads to a supercritical secondary "pearling"
instability. Sufficient changes in the amplitude a lead to subcritical
secondary "doubling" and "bulging" instabilities. Our findings are summarized
in a "stability balloon" for vortex ripple pattern formation.Comment: 4 pages, 5 figure
Squeezed state purification with linear optics and feed forward
A scheme for optimal and deterministic linear optical purification of mixed
squeezed Gaussian states is proposed and experimentally demonstrated. The
scheme requires only linear optical elements and homodyne detectors, and allows
the balance between purification efficacy and squeezing degradation to be
controlled. One particular choice of parameters gave a ten-fold reduction of
the thermal noise with a corresponding squeezing degradation of only 11%. We
prove optimality of the protocol, and show that it can be used to enhance the
performance of quantum informational protocols such as dense coding and
entanglement generation.Comment: 4 pages, 3 figure
Andreev states near short-ranged pairing potential impurities
We study Andreev states near atomic scale modulations in the pairing
potential in both - and d-wave superconductors with short coherence lengths.
For a moderate reduction of the local gap, the states exist only close to the
gap edge. If one allows for local sign changes of the order parameter, however,
resonances can occur at energies close to the Fermi level. The local density of
states (LDOS) around such pairing potential defects strongly resembles the
patterns observed by tunneling measurements around Zn impurities in
BiSrCaCuO (BSCCO). We discuss how this phase impurity model
of the Zn LDOS pattern can be distinguished from other proposals
experimentally.Comment: 4 pages, 4 figure
Creative Business in Australia Learnings from the Creative Industries Innovation Centre, 2009 To 2015
As the largest ever Australian government investment in creative industries development, the Creative Industries Innovation Centre delivered tailored business services to more than 1500 creative businesses from 2009 to 2015 and provided industry intelligence and advice for public policy and peak sectoral activity. This collection gives an overview of the current ‘state of business’ in Australia’s creative industries – both as an industry sector in its own right and as an enabling sector and skills set for other industries – and reflects on business needs, creative industries policy and support services for the sector. With contributions from the Centre’s team of senior business advisers and from leading Australian researchers who worked closely with the Centre –including experts on design-led innovation and the creative economy – and case studies of leading Australia creative businesses, the book is intended as and industry-relevant contribution to business development and public policy
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