19,759 research outputs found
Multiple charge beam dynamics in Alternate Phase Focusing structure
Asymmetrical Alternate Phase (A-APF) focusing realized in a sequence of 36
Superconducting Quarter Wave Resonators has been shown to accelerate almost 81
% of input Uranium beam before foil stripper to an energy of 6.2 MeV/u from 1.3
MeV/u. Ten charge states from 34+ to 43+ could be simultaneously accelerated
with the phase of resonators tuned for 34+. A-APF structure showed unique
nature of large potential bucket for charge states higher than that of tuned
one. Steering inherent to QWRs can be mitigated by selecting appropriate phase
variation of the APF periods and optimization of solenoid field strengths
placed in each of the periods. This mitigation facilitates multiple charge
state acceleration schemeComment: 10 pages, 8 figure
A Pacific Ocean general circulation model for satellite data assimilation
A tropical Pacific Ocean General Circulation Model (OGCM) to be used in satellite data assimilation studies is described. The transfer of the OGCM from a CYBER-205 at NOAA's Geophysical Fluid Dynamics Laboratory to a CRAY-2 at NASA's Ames Research Center is documented. Two 3-year model integrations from identical initial conditions but performed on those two computers are compared. The model simulations are very similar to each other, as expected, but the simulations performed with the higher-precision CRAY-2 is smoother than that with the lower-precision CYBER-205. The CYBER-205 and CRAY-2 use 32 and 64-bit mantissa arithmetic, respectively. The major features of the oceanic circulation in the tropical Pacific, namely the North Equatorial Current, the North Equatorial Countercurrent, the South Equatorial Current, and the Equatorial Undercurrent, are realistically produced and their seasonal cycles are described. The OGCM provides a powerful tool for study of tropical oceans and for the assimilation of satellite altimetry data
Cs adsorption on Si(001) surface: ab initio study
First-principles calculations using density functional theory based on
norm-conserving pseudopotentials have been performed to investigate the Cs
adsorption on the Si(001) surface for 0.5 and 1 ML coverages. We found that the
saturation coverage corresponds to 1 ML adsorption with two Cs atoms occupying
the double layer model sites. While the 0.5 ML covered surface is of metallic
nature, we found that 1 ML of Cs adsorption corresponds to saturation coverage
and leads to a semiconducting surface. The results for the electronic behavior
and surface work function suggest that adsorption of Cs takes place via
polarized covalent bonding.Comment: 8 pages, 7 figure
The Chinese zombie firm: dilemma and resolution
The problems of over-capacity of zombie firms in China have
attracted much attention. However, little is known theoretically,
and even less empirically, about the boundaries and causes of
zombie enterprises. This article extends a model to identify the
characteristics of zombie firms in consideration of supply-side
structural reform in China. We focus on the cause of zombie firms
under the background of the ‘de-capacity’ strategy in China.
Using a sample of Chinese listed companies over the period
2006–2018, we find that the proportion of zombie firms in the
manufacturing industry declined significantly due to expansionary
fiscal policy in 2011. Moreover, the structure of ownership, operational
capabilities, and debt-paying ability co-varies positively,
with state-owned enterprises being most prone to becoming
zombie firms. The results allow us to construct various insights
into how to govern the zombie firm. These results offer a frame
for dealing with zombie firms. Our results are also robust in the
sensitivity test of changing the measurement of zombie firms
A Hybrid Quantum Encoding Algorithm of Vector Quantization for Image Compression
Many classical encoding algorithms of Vector Quantization (VQ) of image
compression that can obtain global optimal solution have computational
complexity O(N). A pure quantum VQ encoding algorithm with probability of
success near 100% has been proposed, that performs operations 45sqrt(N) times
approximately. In this paper, a hybrid quantum VQ encoding algorithm between
classical method and quantum algorithm is presented. The number of its
operations is less than sqrt(N) for most images, and it is more efficient than
the pure quantum algorithm.
Key Words: Vector Quantization, Grover's Algorithm, Image Compression,
Quantum AlgorithmComment: Modify on June 21. 10pages, 3 figure
Toolbox for entanglement detection and fidelity estimation
The determination of the state fidelity and the detection of entanglement are
fundamental problems in quantum information experiments. We investigate how
these goals can be achieved with a minimal effort. We show that the fidelity of
GHZ and W states can be determined with an effort increasing only linearly with
the number of qubits. We also present simple and robust methods for other
states, such as cluster states and states in decoherence-free subspaces.Comment: 5 pages, no figures, v3: final version, to appear as a Rapid
Communication in PR
Comparative performance of squeeze film air journal bearings made of aluminium and copper
This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. Copyright @ 2012 The Authors - The article can be accessed from the links below.This article has been made available through the Brunel Open Access Publishing Fund.Two tubular squeeze film journal bearings, made from Al 2024 T3 and Cu C101, were excited by driving the single-layer piezoelectric actuators at a 75-V AC with a 75-V DC offset. The input excitation frequencies were coincident with the 13th modal frequency, at 16.32 and 12.18 kHz for the respective Al and Cu bearings, in order to produce a ‘triangular’ modal shape. The paper also provided a CFX model, used to solve the Reynolds equation and the equation of motion, to explain the squeeze film effect of an oscillating plate with pressure end leakage. The dynamic characteristics of both bearings were studied in ANSYS and then validated by experiments with respect to their squeeze film thickness and load-carrying capacity. It was observed that whilst both bearings did levitate a load when excited at mode 13, the Al bearing showed a better floating performance than Cu bearing. This is due to the fact that the Al bearing had a higher modal frequency and a greater amplitude response than the Cu bearing.This article is made available through the Brunel Open Access Publishing Fund
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